Cancer can develop in any tissue of any organ at any age. Most cancers detected at an early stage are potentially curable; thus, physicians need a heightened awareness of predisposing inherited and environmental factors. The ability to screen patients for genetic predisposition for cancer can greatly assist in the monitoring of high-risk patients for early signs of cancer, and thus allowing for early intervention. (See for example, The Merck Manual of Diagnosis and Therapy, 16th ed., Merck & Co., (1992)).
Malignant brain tumors (for example glioma, meningiomas, and schwannomas) are common, with an incidence of 4.5 per 100,000. The most common tumor types in adults are gliomas and meningiomas. The most common tumors in children are astrocytomas, medulloblastomas, ependymomas, and brain stem gliomas. In children, brain tumors are one of the most common causes of death from cancer. (See for example, Professional Guide to Disease, 3rd ed., Springhouse Corp., (1989)).
Clinically, brain tumors can be characterized by their cell type and location, along with other phenotypic clues. Malignant brain tumors are sometimes catagorized as glioblastoma multiforme (spongioblastoma multiforme), astrocytoma, oligodendroglioma, ependyoma, medulloblastoma, meningioma, schwannoma, and pituitary tumors. It is also possible that cancer originating in other tissues, such as lung, liver, pancreas, colon, prostate etc., can metastasize to the brain, thus forming tumors that are not of brain origin, potentially causing confusion as to the source of cancer.
Cancer is a cellular malignancy whose unique trait--loss of normal control mechanisms--results in unregulated growth, lack of differentiation, and ability to invade local tissues and metastasize. Thus cancer cells are unlike normal cells, and are potentially identifiable by not only their phenotypic traits, but also by their biochemical and molecular biological characteristics. In particular, the altered phenotype of cancer cells indicates altered gene activity, either unusual gene expression, or gene regulation. Identification of gene expression products or proteins associated with cancer cells will allow for the molecular characterization of malignancies. The ability to specifically characterize suspected cancers, and to potentially identifiy not only cell type, but also predisposition for metastasis and any sensitivity to particular anti-cancer thereapy, is most useful for determining not only the course of treatment, but also the likelihood of success.
Thus, the discovery of specific, brain tumor characteristic gene expression is a useful and important tool useful in screening for, diagnosis of, monitoring of, and therapeutic treatment of brain cancer.